According to the power consumption characteristics of the power grid, the requirements of LED characteristics, and related LED products, the following points must be considered when selecting LED driving power:
a. According to LED current and voltage characteristics, it is ideal to use constant current drive. It can avoid the current change caused by the change of LED forward voltage, and the constant current makes the brightness of the LED stable.
b. In addition, the LED luminous flux is inversely proportional to the temperature, so the power supply should be minimized and a well-designed cooling system should be used during use. Thereby reducing the ambient temperature at which the LED operates.
c. In order to ensure the overall life of the LED product, the junction temperature of the LED must be controlled within a certain range, that is, the working environment temperature of the LED product must be controlled.
LED products are mainly composed of LED chip and power supply, heat dissipation shell, control circuit and so on. The quality of the LED power supply directly affects the quality of the product. In particular, LED street light products are installed at high altitudes, making maintenance inconvenient and expensive.
LED is an energy-saving product, and the driving power supply must also meet the energy-saving requirements. Especially the structure in which the power supply is installed in the luminaire is particularly important. Because the luminous efficiency of the LED decreases as the temperature of the LED increases. The efficiency of the power supply is high, its power consumption is small, the heat generation in the lamp is small, and the temperature rise of the lamp is reduced. It is beneficial to delay the light decay of LED.
3.Constant current drive method
In order to match the volt-ampere characteristics of the LED, the LED power supply must use a constant current drive method.
The impact resistance of LED is relatively poor, so it is necessary to strengthen the protection in this regard. Especially for some products installed outdoors, the start and stop of the grid load and lightning strikes will impact the power supply. Therefore, the input end of the LED driving power supply must have a protection circuit to suppress the surge to prevent the switch from damaging the LED momentarily.
5.Temperature protection function
In addition to the conventional protection function of the power supply, it is best to add negative feedback of the LED chip temperature to the constant current output to prevent the PN junction temperature of the LED chip from becoming too high.
6, LED power life
To improve the life of LED driving power, we need to improve it in many ways: use capacitors with higher life, improve power efficiency, do a good job of cooling the power supply, and optimize the heat dissipation design of the lamp. LED power supplies are switching power supplies. The quality and reliability of a switching power supply depends on its circuit design, production process, and device quality. Electrolytic capacitors are an essential part of high-power switching power supplies. The normal working life of a switching power supply depends on the life of the electrolytic capacitor used by the power supply. The life of the electrolytic capacitor depends on the life of the capacitor itself and the operating temperature. The operating life of the electrolytic capacitor varies greatly at different temperatures.
Due to the different environments in different places, we must focus on the environment of the LED lighting workplace, such as temperature, humidity, and installation location.
Considering the working mode of the power supply, if no soft-start circuit is added, the output will have a voltage spike immediately after power-on. In order to better protect the LED, a soft-start circuit is needed. This is a key factor in driving power stability.